Inside Health

RE: FRAMING; Genetic Tests Offer Promise, but Raise Questions, Too

By DENISE CARUSO

Published: February 18, 2007

A GROWING industry is hoping to spin gold from DNA's double helixes by using ultrasensitive genetic tests to personalize medical treatment for cancer, lupus and other diseases.

These molecular diagnostic tests can give doctors more detailed information than ever about their patients. Genetic information can help them decide whether their lymphoma patients would respond better to surgery, chemotherapy or radiation treatment; make more accurate diagnoses of abnormal cells or tissues; and more readily detect serious autoimmune disorders.

What's more, the development of genetic tests has given academic researchers the tools to begin establishing causal links between common bacteria and viruses -- streptococcus, say, or influenza -- and diseases like autism, cervical cancer, Type 1 diabetes, schizophrenia and even obsessive-compulsive disorder.

More than 1,000 genetic tests are available clinically, and hundreds more are available to researchers. Despite the tremendous promise of these tests, there is growing concern among researchers and patient advocates about how consistently their claims match reality. How accurate are they at finding potential genetic problems? Are different tests for different conditions equally reliable? And how tight is the connection between a genetic trait and a specific illness?

Some researchers say they believe that the practical relevance of many tests has been oversold. Over the last two decades, for example, there has been a steady stream of news about researchers discovering ''the gene'' that links people to diabetes, Alzheimer's, obesity, schizophrenia, depression and many other afflictions.

Yet most of those hard-wired gene-disease links -- as many as 95 percent of them, according to one British study published in 2003 -- don't hold up to closer scrutiny. Instead, follow-up studies find that if there is any measurable genetic link to these common diseases, it results from the more complex interactions of many genes with one another, as well as with the environment.

According to the Human Genome Project, this state of affairs is particularly troubling, considering that a few companies have started marketing genetic tests directly to the public -- sometimes claiming their kits not only test for disease, but can also customize medicine, vitamins and diet to an individual's genetic makeup.

There is no independent review or government oversight of the validity of these tests, particularly those available to consumers through their doctors. No agency yet has the formal responsibility to make sure that genetic tests can produce correct answers reliably over time -- or, more important, that there is even a relationship between a particular genetic variation and a person's health.

Companies that spend millions of dollars and years establishing the clinical utility of their products can find themselves competing in the marketplace with ''a company with a couple of genes it ran on 30 samples,'' as one frustrated industry executive put it.

Add to this mix the relentless churn of new, often conflicting scientific information about the role of genetics in disease -- and the life-or-death nature of the medical decisions that doctors and patients might make, based on results of genetic tests. On what basis should we decide whether these tests are worth getting our hopes up?

''Advances in technology change the types of questions researchers can ask,'' said Dr. W. Ian Lipkin, a doctor and professor of epidemiology, neurology and pathology at Columbia University.

''New tools for detecting and discovering pathogens, new sample collections and new research models will allow us to head off future outbreaks of infectious disease and to meet the challenges at the intersections between gene and the environment,'' Dr. Lipkin added. ''But technology is like a car with a lot of horsepower. If you point it in the wrong direction, you can run people over.''

Dr. Lipkin is director of the Jerome L. and Dawn Greene Infectious Disease Laboratory and scientific director of the Northeast Biodefense Center at Columbia. For many years he has been a significant player in the worlds of infectious disease and biodefense, and is recognized for his interest and skill in developing tools for discovering pathogens and the relationships between pathogens and disease.

Because they are developed and used primarily for research, not clinical practice, genetic tests developed by scientists like Dr. Lipkin are not subject to oversight. But neither are the 1,000 or so commercial genetic tests available to consumers through medical professionals.

Commercial laboratories do not have to negotiate any formal approval process before offering a new genetic test, ''and government requirements to ensure that genetic testing laboratories are getting the right answers to patients are minimal,'' according to an issue brief by the Genetics and Public Policy Center at Johns Hopkins University last September.

What's more, the center added, there is no government requirement that a test must ''actually relate to a particular disease or risk of disease'' in order to be sold.